Drafting instrument



July 18, 1950 2 Sheets-Sheet 1 Filed June 11, 1946 y 1950 H. WAHLE2,515,679

DRAFTING INSTRUMENT Filed June 11, 1946 2 Sheets-Sheet 2 gwue/rvbom E 22Ballad/Vail? Patented July 18, 1950 UNITED STATES PATENT OFFICE DRAFTINGINSTRUMENT Rolla H. Wahle, Portland, Oreg. Application June 11, 1946,Serial No. 676,030

2 Claims. 1

This invention relates to a drafting instrument and more particularly toa drawing pen.

Drawing pens of the type now commonly used comprise a holder with abifurcated member extending therefrom forming opposing pen blades whichblades are adapted to be adjusted relatively so as to provide a pencapable of producing lines of various widths. However, as is well known,such pens are not capable of producing lines of a width as great as isfrequently required, because of the fact that when the pen blades arespread to produce the desired width line, the ink fi-ows too freely anda uniform line becomes impossible. Oftentimes, when producing a wideline, ink flows from the pen so rapidly that a spot is deposited andthus the drawing to that point is ordinarily spoiled beyond usage.

Another disadvantage, particularly in producing wide width lines is thatsuch ink as is deposited within the confines of the space between theblades is not deposited uniformly; near the center of the line much moreink is'deposited than at the edges. Furthermore a greater quantity ofink is always deposited than is needed. This results in a line ofnon-uniform character as to density of color and one which isunnecessarily slow to dry.

The prior art discloses a pen which is provided with broad markingelements so that it may be used to produce a wide line corresponding inwidth to that of the blades. Such a pen however is not satisfactory foruse with a straight-edge because when the blades are placed adjacent thestraight edge, the ink reservoir is also adjacent the straight-edge andink flows from the reservoir to the drawing surface, thus spoiling it.

vIt has also been proposed to uses. pen having broad blades and beingprovided with a guide leg whereby the ink reservoir does not contact thestraight-edge, but thi pen is not satisfactory for a number of reasons.

aFirst this pen does not solve the problem of preventing ink fromgetting on the guide leg. Secondly, it is incapable of holding asufiicient quantity of ink for its purpose without permitting ink toflow down the guide leg. Thirdly, extreme difficulty is encountered inmaking line junctures with this pen because of the width of thebladesadjacent the drawing surface; the pen itself presents an obstructionwhich prevents visual anticipation of the juncture being exeouted.

. It is an object of this invention to overcome the foregoingdisadvantages and to provide a pen of" the side-flow type in whichdifficulties with ink contamination of the guide leg are avoided, andwherein line junctures may be easily visually anticipatedf It iscontemplated according to this invention that a high ink capacity,accurate marking instrument be provided that is characterized by ease ofoperation and high visibility with respect to line junctures.

Other objects and advantages will become evident from the followingdetailed description and drawing wherein: v

Figure 1 is a side view of the pen of this invention;

Figure 2 is a rear view of the pen of Figure 1;

Figure 3 is a sectional view on the line 3-3 of Figure 1;

Figure 4 is a bottom View of Figure 1;

Figure 5 is an inside View of a fragmentary portion of the right bladeof the pen;

Figure 6 is a fragmentary front view of the marking elements;

Figure '7 is a fragmentary side view of a, modified form of the pen ofthis invention;

Figure 8 is a rear view of Figure 7;

Figure 9 is a sectional view on the line 9-9 of Figure '7.

Referring now to Figure 1 of the drawing, numeral It denotes a penholder of any suitable form and material. Extending from holder in is abifurcated member comprising right and left blades i i and i2respectively as is shown in Figure 2. A screw I3 is provided to effectadjustment of the blades. The head of the adjusting screw maybecounter-sunk in one of the blades if desired, since it is contemplatedthat its setting will not be altered except at times when the pen; issharpened. As is shown in Figure 2,

the blades are compressed at their ends remote from the holder to forman ink reservoir.

.In Figure 5, which is an inside View of a frag-" mentary portion of theright blade, a cutaway portion M and a slit l5 divide the right bladeinto a marking element 56 and a. guide leg M. It should be noted thatguide leg I l is beveled toward the cutaway portion M on its inside andoutside.

from its outsidetoward the cutaway portion asshown at 2B.

In use, the marking elements are adjusted relative to each other in amanner hereinafter.

described to provide an ink reservoir and a narrow ink outlet throughwhich ink flows to the drawing surface. Movement of the pen is from leftto right with the guide-leg in sliding contact with the straight-edgeand drawing surface. The marking elements move in contact with thedrawing surface in a line parallel to the straight-edge.

It should be noted that both blades are provided with marking elementswhich are of great width relative to their thickness, the reason forthis being that the pen is primarily designed to produce wide lines. Byvarying the width of the marking elements, a pen which is capable ofdrawing any width line may be provided.

It was pointed out above that by cutting away a portion of blade ll theblade is divided to form the marking element l6 and a guide leg ll.Cutting this portion away from blade l I and the segment from blade 12serves still another purpose in that, when properly done, the draftsrnanmay see the drawing surface between the guide leg. and marking elementthereby facilitatinghis work.

In order to provide a pen which will afford visibility to the drawingsurface so that it will be possible to actually see a line to be joinedas the drawing pen approaches it, it is necessary to cutawayasubstantial portion from eachblade. It has been found that a slitof-aabout /3" length and about /3 in width. in the right blade and acorresponding portion from the left blade will afford suflicient view;however,. a larger opening may be provided if desired. A- lessrestricted view is afforded by the pen shown in Figure I because theleft blade there has a segment cut from it rather" than a slit. It hasalso been found that by beveling the surface of the left blade and guideleg toward the cutaway portion, sharper vision to the drawing surface isafforded.

Another feature of this invention which is important to note is theposition of the guide leg with respect to the marking elements. Theguide leg is beveled toward the inside and therefore a sharp inside edgeis formed which extends substantially vertically from a point adjacentthe lower end of the leg where it contacts the paper; In Figures 2 and 4the tipof the guide leg H is shown as centrally positioned in the planewhich passes through the central points between the marking elements.Such positioning is accomplished by forming a permanent bend or curve inthe guide leg as shown in Figure'2. Thus wardly from the cutawayportion" isto provide a larger ink reservoir and at the same time"prevent the ink from flowing downwardly on the guide leg. In filling thereservoir, it is not contemplated that the ink level will rise abovethe" upper edge of the slits, for if it should, ink

may flow downthe guide leg and thus defeat Furthermore, the surthepurpose of the slits. face tension of the ink in the lower part ofthe ink reservoir is insufficient to support a great quantity of ink andthe slits provide the" maximum-reservoir taking the tension factor into4 consideration. The widest presently contemplated width of the markingelements will produce a line approximately 28 inches in length with onefilling of the ink reservoir. Narrower widths of marking elements willproduce a correspondingly longer line per ink reservoir filling.

Another feature which is important to high ink capacity is the angle ofinclination of the blades to their central plane. Ordinarily, pens areprovided with a curved blade and opposed straight blades. However, byinclining the blades equally from their central plane, greater spacebetween them is provided and thus the capacity of the reservoir isincreased. Suitable angles of inclination are shown in connection withFigure 6.

I The modification of the invention shown in Figure '7 provides adrawing pen which embodies two sets of opposed marking elements 2| and22. each set of different width, so that two lines of different widthsmay be drawn with the same pen. This modification includes the featureof the cutaway portion and the slits extending up wardly, as abovedescribed, in both blades.- However, instead of dividing one of theblades into a a marking element and a guide element, each blade isprovided with a legwhich legs consti tute the second setof markingelements 22. The left blade of the pen of this modification is simi larin all respects to the right blade; in fact, it may be said tobe amirror image of the right blade. The edges surrounding the cutawayportion in the left blade are beveled inwardly toward the cutawayportion as and for the purpose'set forth above. Each set of markingelements has its own reservoir as provided by the sides of the blade andthe upwardly extending slits.

In using this modified form only one set of marking elements is suppliedwith ink at a time, depending upon which width line is desired. It

' is not desirable-to fill both reservoirs at the same time: because oneset of marking elements must act as a guide leg andthus its reservoirwould be adjacent thestraight-edge. If this reservoir contains ink, suchink may flow under the straight-edge and spoil the drawing. In all otherrespects, this form of the pen is manipulateda's is that shown in-Figure 1.

Each marking element of both forms of the invention sharpened downwardlyto-a thin edge so as to afford the least frictional resistance to thepaper. In adjusting the ink outlet be tween the marking elements it isdesirable to have as little space therebetween as is possible and at thesame time maintain a steady flow of ink. The proper width can be arrivedat by any one skilled in using drafting instruments, although it may bewell to point out that as the width of the space between markingelements is increased, a greater quantity of ink flows from thereservoir and this condition may lead to an uneven line, since as thepen moves across the paper, the trailing edge of the left markingelement tends to push a quantity of ink along with it,-thus-creating aslight build-up of ink at the end of the line. This build-11p does notresult when-theink outlet is wide enough only to per-' mit steady inkflow.

duce an edge which is curvilinear. A mere touch of the pen to the paperwill produce' a straight line of length and width corresponding to-thatoftheinkyoutletand movement a short distance to the right or left willproduce a square dot ordash perfectly rectangular because such movementactually results in depositing a series of straight lines each of equallength and touching on their long sides.

In order to assure that the marking elements will at all times contactthe paper properly the guide leg utilized in the first modification ofthis invention should terminate at its paper contacting end in the sameplane as the marking elements.

While the aforesaid has related only to the production of straightlines, it is obvious that curved lines may be produced either by use ofa curved edge guiding instrument such as the French curve or by adaptingthe bifurcated members to use in a compass.

I claim:

1. A drawing pen comprising, a pair of blades,

each of said blades including a wide shank por tion and a narrowinternally and externally beveled marking portion, means for holdingsaid blades in marking position with a V-shaped ink reservoir definedbetween the marking portions, one of said blades including an integralguide leg spaced from the marking portion thereof, said one blade andguide leg defining therebetween a notch wide at its mouth and extendingsubstantially above the beginning of the wide shank portion of the otherblade whereby the ink held between said beveled marking portions cannotflow to the guide leg to foul the coaction thereof with a straight edge,said guide leg having a sharp inside edge extending substantiallyvertically and located centrally along the length thereof and being bentso that the midpoint of the paper contacting edge of said leg lies inthe plane which passes through the central points between the markingelements.

2. A drawing pen as claimed in claim 1 wherein the said guide leg isbeveled toward the said notch whereby the said sharp inside edge isproduced and visual anticipation of a line juncture is facilitated.

, ROLLA I-I. WAHLE.

REFERENGES CITED The following references are of record in the file ofthis patent:

UNITED STATES PA'I'EN'I'S- Number Name Date 265,385 Stokes Oct. 10, 1882510,966 Fuller Dec. 19, 1893 1,287,623 Bieser Dec. 17, 1918 1,902,865Koester Mar. 23, 1933 FOREIGN PATENTS Number I Country Date 444,477Germany 1927

